Frequency tunability of axial cavity vircators and double anode vircators
Sammanfattning: This master thesis investigates the possibility of constructing a continu-ously tuneable virtual cathode oscillator (vircator), which can be used as a radiation source in high power microwave susceptibility testing carried out by the electrophysics group at the Swedish Defence Research Agency (FOI). To determine if a vircator can be made continuously frequency tuneable in a 10 %bandwidth around a central frequency lying within the S-band two vircator designs, the first an axial cavity vircator and the second a double anode vir-cator, are evaluated with electromagnetic particle-in-cell simulations using the software Magic3D. This thesis study focus on achieving continuous frequency tuning in the two vircators’ using a minimal number of tuning parameters. The axial cavity vircator is found to achieve too narrow tuning bands. Combined with issues of occasional poor frequency stability and poor radiated microwave power, the axial cavity vircator is concluded to not be a suitable radiation source for high power microwave susceptibility testing. For the double anode vircator a 10 % tuning band is observed around 2.24 GHz. The double anode vircator also has good frequency stability and radiated microwave power across the observed tuning band and is therefore concluded to be a suitable radiation source for high power microwave susceptibility testing.
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